Absorbent articles for personal hygiene of the type indicated above are designed to absorb and contain body exudates, in particular large quantity of urine. These absorbent articles comprise several layers, for example a topsheet, a backsheet and in-between an absorbent core, among other layers. The function of the absorbent core is to absorb and retain the exudates for a prolonged amount of time, minimize re-wet to keep the wearer dry and avoid soiling of clothes or bed sheets.
The majority of absorbent cores comprise an absorbent material within a core wrap. A first type of commonly used absorbent material is a blend of comminuted wood pulp (so-called “air-felt”) with superabsorbent polymers (SAP) in particulate form, also called absorbent gelling materials (AGM). Another type of cores having SAP as absorbent material without cellulose fibers (so called “airfelt-free” cores) has been more recently proposed.
Fluid-distributing channels extending longitudinally have been proposed for both types of cores. The channels can distribute an insulting fluid quickly along a greater area of the absorbent core thus improving fluid acquisition and optimizing absorbent material usage. Channels may also be used to facilitate the folding of the absorbent core in a pre-determined fashion, thus improving the anatomical conformity of the article. Various channel designs have thus been suggested. In air-felt cores, channels may be provided for example by locally embossing the absorbent material. Channels may also be provided by zones substantially free of absorbent material and surrounded by absorbent material. The top layer of core wrap may be attached to the bottom layer of the core wrap through these areas substantially free of absorbent material by a core wrap bond (herein “channel bond”), so that the channels are more resilient to the movement of the wearer or the swelling of the core with a fluid. The core wrap typically comprises one or two layers of a nonwoven synthetic material, typically PP or PE. The channel bonds may be provided by various means such as gluing, pressure, heat and/or ultrasonic bonding of the core wrap. On the other hand, it is simpler and less costly for the manufacturer to not bond the core wrap through the channels. The presence of channels in an absorbent core can be difficult to recognize before use because modern absorbent articles can be very thin. WO2015/039062 suggests creating a signal to highlight the channels for example by printing a printed adhesive layer between the topsheet and the absorbent core. WO2012/014436A1 discloses a disposable absorbent article having a display area adapted to be visually recognized from both an inner side and an outer side of the article. The liquid absorbent structure is formed with central void and lateral voids. The display area can be visually recognized from the garment-facing side through the central void. The display area may comprise a urine indicator.